## rational number
The missing numbers can easily be seen by plotting sets of numbers along the number line. Th emethod also involves mapping one set of numbers on to the set of integers on the number line. The ordered pair notation is perhaps the most useful and versatile. Fractions need two numbers (the numerator and denominator of the fraction) to define them. In the usual fractional form, the numbers are set one over the other. In the ordered pair notation, they are set one after the other. ## Sets of ordered pairsThe set of rational numbers1/3, 2/3, 3/3, 4/3,...have one thing in common. They are all numbers of thirds. 3 is the denominator of each of the fractions. In other words, they all belong to the set of thirds. In the ordered pairs of notation, the same set is written as (1, 3), (2, 3), (3, 3), (4, 3),...Ordered pairs from a useful set when the second number of the pair is the same for each ordered pair. In particular, this simplifies the rules for adding and subtracting the pairs. ## Related category• NUMBER THEORY | |||||||||

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